Not Applicable.
Not Applicable.
1. Field of the Invention
This invention relates generally to lumbar support devices and particularly to lumbar support devices that are capable of changing shape, especially curvature in the lumbar region.
2. Description of Related Art
Lumbar support devices have been integrated into seats to change their shape, thereby allowing each occupant to adjust the support provided by the seat The curvature of these devices are traditionally adjustable so that an occupant can operate the device to push the seat forward towards the occupant""s spinal column in the lumbar region. It is generally known to change the curvature of a lumbar support device using an actuator assembly that moves a support structure. It is also well known to provide an actuator assembly with an effector that is either manually operated, using a handle or a knob, or power-assisted, using a drive motor and control switches. Increased curvature is usually accomplished by moving the support structure forward into the lumbar region, rotating sections of the support structure into the lumbar region, or bowing the support structure out into the lumbar region. As discussed below, these known devices operate on the general principles of increasing the firmness or stiffness of the support structure and changing the shape of the lumbar support device. Many devices produce a uniform curvature across the lumbar region such that the sides of the support structure curve as much as the center portion of the support structure. However, these devices do not increase the stiffness of the support structures. Similarly, a prior art device that increases the stiffness of the support structure does not produce a uniform curvature across the lumbar region. It would be good to increase the stiffness of the support structure and also provide uniform curvature across the support structure.
Examples of lumbar support devices in which the support structure is moved forward into the lumbar region are found in U.S. Pat. No. 4,159,847 and U.S. Pat. No. 5,452,868. In the first invention, the device is secured to a frame such that the support structure is in tension even in a relaxed position. A handle attached to a pair of levers linked to opposite sides of a grid. By rotating the handle, the pair of levers rotate and the grid is thereby moved forward into the lumbar region. Each lever is linked to the grid through a coil spring that produces the tension across the support structure and provides the support structure with a stiffness. Similarly, U.S. Pat. No. 5,452,868 discloses a lumbar support device that uses a single powered lever that to push a lumbar support panel forward into the lumbar region. Although the levers in these inventions uniformly move the support structure forward, they do not increase the stiffness of the support structure.
Examples of lumbar support devices in which sections of the support structure are rotated into the lumbar region are found in U.S. Pat. No. 4,564,235 and U.S. Pat. No. 5,823,620. In the first invention, a pair of plates are rotated into the lumbar region. The plates are situated laterally across the lumbar region and thereby provide uniform curvature across the support structure. However, the tension across the plates is not increased when the plates are rotated and the stiffness of the plates is not increased. The lumbar support device disclosed in U.S. Pat. No. 5,823,620 uses a bowden cable in the actuator assembly to rotate a pair of levers that respectively rotate a pair of pads into the lumbar region. The pads are situated horizontally and do not provide uniform curvature across the support structure, and the stiffness of each lever and its respective pad is not increased.
Examples of lumbar support devices in which the support structure is bowed out into the lumbar region are found in U.S. Pat. No. 4,588,172 and U.S. Pat. No. 5,651,584. In the first invention, the support structure is formed by a sinusoidal spring attached to a grid and positioned between two discs. The discs are attached to a rod and skewed in opposite directions, and a handle is attached to one end of the rod. By rotating the handle from a relaxed position, the rod rotates and the skewed discs rotate away from each other, thereby pulling the spring tighter and flexing the center portion of the spring into the lumbar region. The sinusoidal spring is bowed forward, increasing the tension in the support structure. Although the increased tension increases the stiffness of the support structure, the spring bows laterally across the lumbar region causing a bulge in the center of the lumbar region and resulting in negligible curvature at each side of the lumbar region. Therefore, the lumbar region of a person sitting in such a seat would not be supported at the sides as with a device that produces a uniform curvature across the lumbar region. For example, U.S. Pat. No. 5,651,584 bows a support structure such that a uniform curvature is produced across the lumbar region.
Typically, many lumbar support devices use levers in the actuator assemblies. For the lumbar support devices that use levers, the support structures and actuator assemblies in these devices are generally constructed of materials that are manufactured from individual components and attached by hardware, such as rivets, screws, wire-ties, welds and bolts. Therefore, the designs of these devices require manual assembly operations, including the manual attachment of coil springs and sub-assemblies requiring rivets or welds, and are not well suited for a simplified assembly process.
It is in view of the above problems that the present invention was developed. The invention is a lumbar support device, preferably for use in a seat frame, having a support structure attached between a pair of levers that are rotated by an actuator assembly. In one embodiment, the support structure is formed by a grid having multiple flexible wires securely wrapped around a pair of border wires at opposing sides of the support structure. The support structure has an integral spring formed by a sinusoidal pattern of the multiple flexible wires. Each of the pair of levers is formed from a serpentine wire that wraps around a bar that is secured to the seat and wraps around one of the border wires. The actuator assembly uses a hook and a hooked rod to link the pair of levers, and a bowden cable connects an effector with the hook and the hooked rod. The effector pulls on the bowden cable causing the hook and hooked rod to pull on the pair of levers and resulting in the rotation of the levers. In response, the levers move the grid into the lumbar region, thereby producing uniform curvature across the support structure, and pull the grid in tension, thereby increasing the support structure""s stiffness.
In another embodiment, the support structure has a pair of coil springs attached between the pair of levers. The pair of levers are secured to the seat frame. As in the first embodiment, the actuator assembly uses a hook and a hooked rod to link the pair of levers, and a bowden cable connects an effector with the hook and the hooked rod. The effector pulls on the bowden cable causing the hook and hooked rod to pull on the pair of levers and resulting in the rotation of the levers. In response, the levers move the support structure into the lumbar region, thereby producing uniform curvature across the support structure, and pull the support structure in tension, thereby increasing the stiffness of the support structure.
Therefore, it is an object of this invention to provide a lumbar support device capable of increasing the stiffness of the support structure and producing uniform curvature across the support structure.
It is another object of the present invention to provide a lumbar support device capable of producing uniform curvature movement with a lever and support structure that uses fewer parts and hardware than the related art.
It is yet another object of the present invention to provide a process for increasing the stiffness and curvature of a lumbar support device.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.